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Publication numberUS6906638 B2
Publication typeGrant
Application numberUS 09/984,286
Publication dateJun 14, 2005
Filing dateOct 29, 2001
Priority dateNov 17, 2000
Fee statusPaid
Also published asUS20020060627
Publication number09984286, 984286, US 6906638 B2, US 6906638B2, US-B2-6906638, US6906638 B2, US6906638B2
InventorsMartin Gaiser
Original AssigneeVega Grieshaber Kg
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sensor unit
US 6906638 B2
Abstract
A sensor unit (9) for measuring a process magnitude and for producing a digital signal representative of the process magnitude exhibits an interface (3) for transmitting the digital signal in a network (5) that supports communication between a plurality of users.
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Claims(5)
1. A sensor unit (9) for measuring a process magnitude and for producing a digital signal representative of the process magnitude,
wherein said sensor unit exhibits at least one interface (3) for transmitting the digital signal in a network that supports communication between a plurality of users, and
wherein said sensor unit exhibits an initial interface (3) in the form of a modem for communication with a telephone network (5) and a second interface to a LAN network.
2. A sensor unit according to claim 1, wherein said sensor unit includes a filling-level sensor.
3. A sensor unit according to claim 1, wherein the interface includes a modem (3) and the network is a telephone network (5).
4. A sensor unit according to claim 1, wherein the interface is a LAN interface and the network is a LAN.
5. A sensor unit according to claim 1, wherein the first interface serves to interrogate and/or set functional parameters of the sensor unit and the second interface serves to transmit measured values received by the sensor unit.
Description

This application is a nonprovisional of U.S. provisional application No. 60/273,345 filed Mar. 6, 2001.

The present invention relates to a sensor unit for measuring process magnitudes, particularly as they are employed in the monitoring of industrial manufacturing processes.

In a manufacturing facility, sensors are often scattered over a number of points in order to measure magnitudes for the control of the production process. The measuring signals of the sensors must be conducted—frequently over considerable distances—to a guidance monitoring point, where they are correlated with each other and evaluated.

To avoid falsifying the measuring signals over long transmission paths at sometimes low signal amplitudes such monitoring tasks frequently employ sensor units which provide a digital output signal, since this kind of signal can be transmitted over long distances without loss of information. Wiring the sensor units to the guidance monitoring point remains complicated and expensive, however, even for digital transmission.

Another problem, which represents a peculiarity of digital transmission as compared to analog transmission, results from the arbitrary selection capability of formats in the digital display of the measured values. The zero and one levels can be linked with certain intervals of the voltage or current strength; the transmitter of the measured values may exhibit an active current or voltage, or it can be supplied passively with energy from the receiver via the data line and can signal various logical states to the receiver by changes in its load over this line. A transmitted bit sequence may represent a pure measured value or it may contain, in addition to the measured value, parity bits or other types of error identification information, etc. A consequence of this arbitrariness is the fact that digital sensor units and receivers from different manufacturers can hardly be employed together and that receivers, etc. are necessary for all separate wirings when a user is instructed to employ sensor units of different, non-compatible systems.

To solve the problem of wiring expense a sensor was proposed, e.g., in EP 0 949 447, to monitor a steam separator, where the sensor transmits digital signals by radio. To supply the energy needed for the radio transmission, this publication also proposes that the sensor be equipped with solar cells. When this is not practical due to insufficient illumination, there is no alternative, however, but to wire the sensor, this time for the supply of energy.

The goal of the invention is to create a sensor to measure process magnitudes which permits a digital measuring signal obtained by the sensor to be transmitted to a receiver in a standardized form, with simple means that can be obtained cheaply.

To this end it is proposed that the sensor be equipped with an interface for transmitting the digital signal in a network that supports communication between a plurality of users. Such networks are already present in most manufacturing plants, e.g., in the form of a telephone network or a local computer network (LAN). In inserting such a network, consequently, wiring does not have to be made from the sensor to the guidance monitoring point; a connection from the sensor to the nearest network access point is sufficient. Interfaces for networks, modems, or network adapters are produced in large quantities and can be obtained cheaply.

Ideally the sensor units will include a filling-level sensor. The container filling-levels measured by such sensors usually involve slowly changing magnitudes, and the rate at which data is delivered by an individual sensor unit is low. Consequently sensor units of this kind can be attached to the network in large number, without noticeably impeding the network's capacity for its originally intended tasks.

FIGS. 1 and 2 each show an inventive sensor unit, attached to a telephone network.

Attached to a signal outlet of the sensor 1 shown in FIG. 1—a filling-level sensor—is an interface transformer 2, which serves to convert the analog output signal of the sensor 1 into a digital signal, in a form that can be processed by an attached modem 3, e.g., eight or 16 bit parallel with TTL level.

A control unit 4 is attached to the modem 3 parallel to the interface transformer 2. This control unit can serve, e.g., to establish at regular intervals a command to establish a telephone connection over the modem 3 and the telephone network 5 (shown here only schematically as a cable) to a guidance monitoring point, e.g., a workplace computer 6, which is also connected to the telephone network 5 via a modem—the purpose of which is to transmit to the workplace computer 6 an actual measured value of the sensor 1 or a number of measured values collected and stored since the last connection, or to receive a call established by the workplace computer 6 and execute commands received from the workplace computer 6, e.g., a command to transmit measured values, to adjust the sensitivity of the sensor 1, or to adjust other parameters of the sensor 1 or the interface circuit 2.

The sensor 1, the interface transformer 2, the modem 3, and the control unit 4 are combined in a structural unit 9. To install this structural unit 9 it is sufficient to mount the unit on the container, or comparable structure, whose filling level is to be measured, and to lay a connecting cable from the sensor unit 9 to the nearest telephone connecting plug. The energy needed to operate the sensor 1 and the other components of the structural unit is drawn from the telephone plug via the connecting cable, so that the unit does not require its own power line for the supply of current.

As shown in FIG. 2, the same structural unit 9 can also be employed to transmit data with the aid of a cordless telephone terminal 7, e.g., a device according the DECT standard, and with the aid of a private branch exchange 8 adjusted to this device; the data is transmitted to the workplace computer 6. Since energy cannot be supplied over the telephone network 5 in this variant, a power source (not shown) connected to a cable is provided. It is also conceivable to integrate the transmitter-receiver unit employed by this kind of terminal device into the structural unit of the sensor.

In a second embodiment of the invention the modem is replaced by an interface for a local computer network, particularly by an ethernet adapter. This embodiment is preferred when small quantities of data must be transferred at short intervals of time, since here the data transmission is packet oriented and the previous connection structure, which is associated with time and signaling expense, is omitted.

In a third embodiment depicted in FIG. 3 the sensor exhibits, in addition to the modem 3 for communication over a telephone network, a second interface 10 for communication with a network based on a fieldbus 11 such as HART, Profibus, or FF (Fieldbus Foundation). The fieldbus line serves to transmit measured values received by the sensor to a guide computer 12, e.g., an SPS (storage-programmable control) or a PLS (process guide system). The control unit 4 then serves to monitor both transmission paths.

In this embodiment, communication over the telephone line is employed only for interrogating and setting operating parameters of the sensor, e.g., in the context of remote parametering, maintenance, or diagnosis.

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7216659 *Jun 30, 2005May 15, 2007Great Stuff, Inc.Low power system for wireless monitoring of an environment and irrigation control
US7685267 *Oct 25, 2006Mar 23, 2010Vega Grieshaber KgMethod and system for connecting to a field device
US8132592Mar 6, 2009Mar 13, 2012Great Stuff, Inc.Remote control for hose operation
US8739815Mar 12, 2012Jun 3, 2014Great Stuff, Inc.Remote control for hose operation
US9079748Feb 22, 2008Jul 14, 2015Great Stuff, Inc.Remote control for valve and hose reel system
US9504075Nov 25, 2014Nov 22, 2016Vega Grieshaber KgField device apparatus and method for communicating of a field device apparatus with an evaluation device
US20060054214 *Jun 30, 2005Mar 16, 2006Caamano Ramon ALow power system for wireless monitoring of an environment and irrigation control
US20070100995 *Oct 25, 2006May 3, 2007Andreas IsenmannInterface for a database for a field unit
US20080223951 *Feb 22, 2008Sep 18, 2008Great Stuff, Inc.Remote control for valve and hose reel system
US20090301573 *Mar 6, 2009Dec 10, 2009Great Stuff Inc.Remote control for hose operation
Classifications
U.S. Classification340/870.07, 340/538.11, 73/865.8, 340/3.53
International ClassificationG01F23/00
Cooperative ClassificationG01F23/0069
European ClassificationG01F23/00G1
Legal Events
DateCodeEventDescription
Oct 29, 2001ASAssignment
Owner name: VEGA GRIESHABER KG, GERMANY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GAISER, MARTIN;REEL/FRAME:012292/0303
Effective date: 20011018
Dec 1, 2008FPAYFee payment
Year of fee payment: 4
Dec 10, 2012FPAYFee payment
Year of fee payment: 8
Dec 7, 2016FPAYFee payment
Year of fee payment: 12